Vasoocclusive device for treatment of aneurysms

ABSTRACT

The three dimensional device is adapted to be inserted into a portion of a vasculature for occluding the portion of the vasculature for use in interventional therapy and vascular surgery. The device is formed from a multi-stranded microcable having a plurality of flexible strands of a shape memory material and at least one radiopaque strand. The device can be bundled by an outer cover to constrain the strands of the micro-cable about a longitudinal axis to produce a composite banded cable. The radiopaque strand can have a core strand with a plurality of intermittently spaced apart enlarged radiopaque portions that may be a plurality of beads of radiopaque material spaced apart and mounted on the core strand, or a plurality of coils intermittently wound about and spaced apart on the core strand.

RELATED APPLICATIONS

This is a continuation-in-part of Ser. No. 09/019,841 filed Feb. 6, 1998now U.S. Pat. No. 6,159,165, which was a continuation-in-part of Ser.No. 08/986,004 filed Dec. 5, 1997 now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to implantable devices forinterventional therapeutic treatment or vascular surgery, and concerns astranded micro-cable with enhanced radiopacity that can be used tofabricate a vascular device, a stent, a guidewire or the like. Moreparticularly, the invention relates to three dimensional microcoilvasoocclusive devices fabricated from stranded micro-cable.

2. Description of Related Art

The art and science of interventional therapy and surgery hascontinually progressed towards treatment of internal defects anddiseases by use of ever smaller incisions or access through thevasculature or body openings, in order to reduce the trauma to tissuesurrounding the treatment site. One important aspect of such treatmentsinvolves the use of catheters to place therapeutic devices at atreatment site by access through the vasculature. Examples of suchprocedures include transluminal angioplasty, placement of stents toreinforce the walls of a blood vessel or the like and the use ofvasoocclusive devices to treat defects in the vasculature. There is aconstant drive by those practicing in the art to develop new and morecapable systems for such applications. When coupled with developments inbiological treatment capabilities, there is an expanding need fortechnologies that enhance the performance of interventional therapeuticdevices and systems.

One specific field of interventional therapy that has been able toadvantageously use recent developments in technology is the treatment ofneurovascular defects. More specifically, as smaller and more capablestructures and materials have been developed, treatment of vasculardefects in the human brain which were previously untreatable orrepresented unacceptable risks via conventional surgery have becomeamenable to treatment. One type of non-surgical therapy that has becomeadvantageous for the treatment of defects in the neurovasculature hasbeen the placement by way of a catheter of vasoocclusive devices in adamaged portion of a vein or artery.

Vasoocclusion devices are therapeutic devices that are placed within thevasculature of the human body, typically via a catheter, either to blockthe flow of blood through a vessel making up that portion of thevasculature through the formation of an embolus or to form such anembolus within an aneurysm stemming from the vessel. The vasoocclusivedevices can take a variety of configurations, and are generally formedof one or more elements that are larger in the deployed configurationthan when they are within the delivery catheter prior to placement. Onewidely used vasoocclusive device is a helical wire coil having adeployed configuration which may be dimensioned to engage the walls ofthe vessels. One anatomically shaped vasoocclusive device that formsitself into a shape of an anatomical cavity such as an aneurysm and ismade of a pre-formed strand of flexible material that can be anickel-titanium alloy is known from U.S. Pat. No. 5,645,558, which isspecifically incorporated by reference herein. That vasoocclusive devicecomprises one or more vasoocclusive members wound to form a generallyspherical or ovoid shape in a relaxed state. The vasoocclusive memberscan be a helically wound coil or a co-woven braid formed of abiocompatible material, and the device is sized and shaped to fit withina vascular cavity or vesicle, such as for treatment of an aneurysm orfistula. The vasoocclusive member can be first helically wound orbraided in a generally linear fashion, and is then wound around anappropriately shaped mandrel or form, and heat treated to retain theshape after removal from the heating form. Radiopacity can be providedin the vasoocclusive members by weaving in synthetic or natural fibersfilled with powdered radiopaque material, such as powdered tantalum,powdered tungsten, powdered bismuth oxide or powdered barium sulfate,which can potentially be released during vascular surgery.

Another occlusion device for closing defects in vascular walls is knownthat is formed by a pair of distinct sections of varying configuration,which may be parabolic or conical bodies oriented to flare outward. Yetanother implantable vasoocclusive device is known that is formed by acomplex, helically wound coil adapted to take on a secondary shapesuitable for snugly fitting within a given vascular cavity upondeployment, that can be formed by winding the coil on a mandrel havingradially extending poles.

The delivery of such vasoocclusive devices can be accomplished by avariety of means, including via a catheter in which the device is pushedthrough the catheter by a pusher to deploy the device. The vasoocclusivedevices, which can have a primary shape of a coil of wire that is thenformed into a more complex secondary shape, can be produced in such away that they will pass through the lumen of a catheter in a linearshape and take on a complex shape as originally formed after beingdeployed into the area of interest, such as an aneurysm. A variety ofdetachment mechanisms to release the device from a pusher have beendeveloped and are known in the art.

For treatment of areas of the small diameter vasculature such as a smallartery or vein in the brain, for example, and for treatment of aneurysmsand the like, micro-coils formed of very small diameter wire are used inorder to restrict, reinforce, or to occlude such small diameter areas ofthe vasculature. A variety of materials have been suggested for use insuch micro-coils, including nickel-titanium alloys, copper, stainlesssteel, platinum, tungsten, various plastics or the like, each of whichoffers certain benefits in various applications. Nickel-titanium alloysare particularly advantageous for the fabrication of such micro coils,in that they can have super-elastic or shape memory properties, and thuscan be manufactured to easily fit into a linear portion of a catheter,but attain their originally formed, more complex shape when deployed.Although various materials are more or less kink resistant whennickel-titanium alloys are dimensioned into wire smaller thanapproximately 0.010 inches in diameter, they can have low yield strengthand can kink more easily, thus severely limiting the applications forsuch finely drawn wire in the fabrication of vasoocclusive devices. As afurther limitation to such applications, nickel-titanium alloys are alsonot radiopaque in small diameters, and a single nickel-titanium wirewould need to be approximately 0.012 inches in diameter to be evenslightly radiopaque. However, such a thickness of a singlenickel-titanium wire would unfortunately also be relatively stiff andpossibly traumatic to the placement site, particularly if used fortreatment of delicate and already damaged areas of the small diametervasculature such as an aneurysm in an artery or vein in the brain, forexample.

One conventional guidewire for use in a catheter is known that is madeof a high elasticity nickel-titanium alloy, and is useful for accessingperipheral or soft tissue targets. The distal tip of the guidewire isprovided with a radiopaque flexible coil tip, and a radiopaque end capis attached to the guidewire by a radiopaque ribbon. Such a constructionis complex to manufacture, fragile and can potentially break off duringuse with undesirable results. A stretch resistant vasoocclusive coil isalso known that can be made of a primary helically wound coil ofplatinum wire, with a stretch-resisting wire attached within the primarycoil between two end caps. Unfortunately, such a construction isrelatively difficult to fabricate and also fragile, allowing for thepossibility of the fracture of the central radiopaque wire, the coil,the welds or some combination of them, and it can also potentially breakoff during use. Also, such a construction has a complex and nonlinearbending characteristic, dependent on the spacing of the coils andcentral wire and the radius of the bend of the coil.

From the above, it can be seen that vasoocclusive devices and theirattendant deployment systems provide important improvements in thetreatment of damaged neurovascular areas. However, there remainimportant limitations in the technology presently available to fabricatethese devices. It would therefore be desirable to provide a structuralelement that can be incorporated into a stent, guidewire, micro-coil orthe like, which offers the advantages of a shape memory alloy such as anickel-titanium alloy, and that incorporates radiopaque material in astable configuration that is not subject to breaking during use of thedevice, so that the device can be visualized under fluoroscopy. It wouldalso be desirable to be able to create a variety of three dimensionalvasoocclusive shapes that can be deployed from a catheter into ananeurysm or other defect and to thereby provide an efficient therapy fortreatment of the defect. The present invention meets these and otherneeds.

SUMMARY OF THE INVENTION

Significant advances have been made in the treatment of neurovasculardefects without resolution to surgery. More specifically, microcatheters have been developed which allow the placement of vasoocclusivedevices in an area of the vasculature which has been damaged. Inpresently used techniques, the vasoocclusive devices take the form ofspiral wound wires that can take more complex three dimensional shapesas they are inserted into the area to be treated. By using materialsthat are highly flexible, or even super-elastic and relatively small indiameter, the wires can be installed in a micro-catheter in a relativelylinear configuration and assume a more complex shape as it is forcedfrom the distal end of the catheter.

In order to gain the advantages presently being realized withmicro-catheter therapies and procedures to repair damage to thevasculature in the brain and other vessels, shape memory materials suchas nickel-titanium alloys have been incorporated in vasoocclusivedevices to be placed by the catheters. However, the range of diametersof wire and the configurations of the resulting geometry of both thecoils and the devices developed which can be used have been limited byboth the relatively small diameter of wire that must be used to avoidtrauma and allow housing within the catheter prior to deployment, andthe requirement for larger diameters to provide for radiopaque markersand mechanical robustness. In many cases this has resulted in primarywire characteristics in the coil that are unacceptably stiff, verydelicate, or subject to kinking. The present invention obtainssignificant advantages over such prior art devices by providing a cableof multiple strands of an alloy adapted to be used in catheters, stents,vasoocclusive devices, guidewires and the like, thus providing a kinkresistant, high strength material with highly desirable performancecharacteristics which can be altered by construction details to suit avariety of interventional therapeutic procedures.

More specifically, it has been found that single strands of smalldiameter nickel-titanium alloys, as well as other metal alloys, used toform vasoocclusive devices can be kinked if twisted and pulled as canoccur during or after deployment from a catheter, especially if thedoctor wishes to withdraw a partially deployed coil because it issomehow incorrect in size, shape or length to repair the damage to thevessel. Also, single wire coils are more likely to cause trauma to thearea to be treated if the wire is of a sufficient diameter to provideadequate tensile strength. Furthermore, such small diameter wires ofsome of these materials such as nickel-titanium, stainless steel and thelike, are not generally radiopaque with currently available equipment,necessitating the use of radiopaque markers attached to the device, withthe resultant possible diminution of functionality and increaseddiameter.

The present invention solves these and other problems by providing, inits broadest aspect, a micro-cable which includes at least oneradiopaque strand to offer a continuous indication under fluoroscopy ofthe deployed configuration of the device incorporating the micro-cable.When combined with the benefits of a material such as nickel-titanium inthe other strands of the micro-cable, numerous advantages are availablefrom the use of this basic construction in interventional medicine.

Briefly, and in general terms, a presently preferred embodiment of thepresent invention provides for a multi-stranded micro-cable made of asuitable material such as stainless steel or a nickel-titanium alloy,with the cable including at least one radiopaque strand, made ofplatinum, tungsten or gold, in order to serve as a marker during aprocedure. The multi-stranded micro-cable can be configured into astent, guidewire, micro-coil or the like used in micro-catheters, forexample, to restrict, reinforce, or to occlude areas of the smalldiameter vasculature such as an artery or vein in the brain, forexample, for treatment of aneurysms and the like.

In one presently preferred embodiment, the invention accordinglyprovides for a multi-stranded micro-cable formed of a plurality offlexible strands of a super elastic material, and at least oneradiopaque strand. In one presently preferred embodiment, themulti-stranded micro-cable comprises a plurality of flexible strands ofnickel-titanium alloy, the micro-cable having at least one centralaxially disposed radiopaque wire, such as platinum, tungsten or gold,for example, in order to provide a radiopaque marker during vascularprocedures. In this preferred embodiment, the construction of theinvention places the lowest tensile strength and highest flexibilitymember, the radiopaque marker strand, in a position in the cable whichresults in minimum stress on that member; at the same time, the superelastic material is in the outer strands, which have the dominant affecton performance parameters, thus enhancing the benefits of the material.Another benefit associated with the invention compared to prior artdevices is that the multiple stranded cable configuration, in additionto providing a highly flexible and resilient structure, eliminates thenecessity of a safety wire, since the failure of a single strand willnot cause a severing of the cable. Also, the construction preventsstretching of the cable in the event of failure of a single strand,which is a significant benefit compared to constructions which have acoil around a central safety wire.

In a second presently preferred embodiment, the invention includes amulti stranded cable constructed of multiple twisted strands of asuitable material such as a shape memory alloy or super elastic alloy ofnickel-titanium, with one or more of the twisted strands consisting of aradiopaque material. The radiopaque strand may be one or more of theperipheral twisted strands and may also include one or more centralstrands of the cable. In a preferred aspect of the embodiment, the cableconsists of six peripheral twisted strands and a central linear corestrand, one or more of which can be of radiopaque material.

In a third aspect of the invention, the cable can be of linear strandsthat are arranged in a bundle and fastened or bound at intervals, orcontinuously, in order to maintain contact among the strands as thecable is bent. One or more of the strands may be radiopaque. Thisconstruction is adaptable to guidewires and other structures that mustbe pushable and/or torqueable, but still remain highly flexible andinclude radiopacity. Variations on this embodiment can include an outersheath which consists of a solid or helically wound cover to provideenhanced torqueability and pushability. More specifically, the outersheath can vary in thickness, stiffness of material or spring of thesheath members to provide desired variations in bending or stiffness ofthe cable. Such a construction is particularly adaptable to guidewiresand the like, and can be varied in terms of the binding or outer layerto alter the torqueability of the cable, and the flexibility of thecable can be varied along its length by the number and sizes of thestranded members in the cable.

In a fourth aspect of the invention, one or more of the strands can beof a therapeutic material used to enhance treatment of the site afterplacement of the device. In one presently preferred embodiment of theinvention, the cable includes twisted strands of wire around theperiphery of the cable, at least one of which is radiopaque. The core ofthe cable contains a therapeutic agent such as human growth hormone,genetic material, antigens or the like that are intended to becomeactive after placement. Such a construction can be adapted to a varietyof interventional therapeutic treatments. In one aspect of thisembodiment, one of the strands can have multiple functions, such asproviding both a therapeutic effect and also contributing to thestructural integrity of the cable. By using copper in such amicro-cable, for instance, the copper can enhance the use of a devicemade from the cable as an intrauterine device, with the copper alsocontributing to the radiopacity and structural integrity of themicro-cable. In the event that such an effect is desired, thetherapeutic strand can be placed on the exterior of the cable to enhancecontact with the site to be treated.

In a fifth aspect of the invention, a three dimensional occlusive deviceis provided that is adapted to be inserted into a portion of avasculature for occluding the portion of the vasculature for use ininterventional therapy and vascular surgery, that comprises at least onemulti-stranded micro-cable having a plurality of flexible strands of aresilient material, with at least one radiopaque strand to provide aradiopaque marker of the deployed configuration of a device made of thecable during vascular surgery. The occlusive device is configured tohave a primary, collapsed coil configuration or shape, and an expanded,or secondary three dimensional coil configuration or shape, that can begenerally helical, conical, or spherical shapes. The flexible strands ina multi-stranded micro-cable of the occlusive device can be helicallywound, or can be configured as parallel, longitudinal strands. In acurrently preferred embodiment, at least one of the strands comprises asuper-elastic material. In another currently preferred embodiment, aplurality of the strands comprises a super-elastic material. Onepresently preferred super-elastic material comprises a nickel titaniumalloy, that can be heat treated such that the alloy is highly flexibleat a temperature appropriate for introduction into the body via acatheter, and after placement, the device will seek its minimum energyshape as originally formed and thereby take on a shape designed tooptimize the therapeutic purposes desired for the device.

In another aspect of the invention, at least one of the strandscomprises a shape memory material. In another currently preferredembodiment, a plurality of the strands are comprised of a shape memorymaterial. One presently preferred shape memory material comprises ashape memory polymer. In one configuration, the strands of themicro-cable are arranged as exterior strands surrounding at least oneinterior strand, or core, and at least one radiopaque strand is disposedin the micro-cable, either centrally, axially disposed in the bundle ofstrands, or in the exterior strands surrounding the central core. Themicro-cable can include a plurality of radiopaque strands, such asplatinum, gold, or tungsten.

In the fifth aspect of the invention, at least one of the strands in thecore or exterior strands can comprise a therapeutic agent, such as acopper or copper alloy wire or any of a variety of therapeuticallyactive metals, alloys or components, a fiber such as Dacron (polyester),polyglycolic acid, polylactic acid, fluoropolymers, nylon, polyaramidfiber (e.g.Kevlar®), or silk chosen for thrombogenicity. Since themicro-cable consists of stranded parts, one or more strands may belonger than others, or even intermittently terminated, to thereby extendbeyond the diameter of the remaining strands and thereby increase thetherapeutic effect of that strand. Alternatively, at least one of thestrands can be coated with or impregnated with a therapeutic material,which can include, but is not limited to, any one or combination ofhuman growth hormone, genetic material, antigens, hydrogels, collagen,bioabsorbable polymers such as lactic acids/glycolic acids, caprolactamor microcellular foam. In addition, the therapeutic element can comprisea means to conduct energy, such as an optical fiber to conduct lightenergy.

In the fifth aspect of the invention, the strands of the micro-cable canalso be bundled by at least one outer cover or sheath to constrain thestrands of the micro-cable about a longitudinal axis to produce acomposite banded cable. The outer sheath can comprise a containmentstrand wound about the strands and made of a low friction material, suchas a fluoropolymer, for example, or a heat shrinkable plastic tube. Inone feature of the fifth aspect of the invention, a plurality of heatshrink plastic covers are placed over the strands of the micro-cable toprovide bending stiffness in the cable. The strands of the micro-cablecan be banded at intervals by a plurality of bands. In anothervariation, a plurality of micro-cables that are arranged as parallel,longitudinal micro-cables or a helically wound micro-cables to form acomposite cable can have an exterior wrapped cover that can be wound atgreater or lesser intervals along the outside to provide variations inthe torqueability and stiffness of the composite cable. Also, thethickness and width of the wrapping cover, as well as its materialcomposition along the composite cable can vary in cross section alongthe length of the composite cable to provide bending stiffness of saidcable which varies with the position on said cable. Also, the number ofstrands and the degree to which they extend along the composite cablecan be varied within the sheath, and the outer sheath itself can bemulti-layered with different materials in order to provide a graduatedbending and stiffness characteristic over the length of the cable. Theocclusive device thus can be formed of a plurality of micro-cables inorder to provide desired bending and strength characteristics, either ashelically wound micro-cables, or parallel longitudinal micro-cableshaving a collapsed composite cable configuration and an expandedcomposite cable configuration with a secondary shape. In another featureof the fifth aspect of the invention, the composite cable can furthercomprise at least one longitudinal sensing element for sensing aparameter, such as an optical imaging element, i.e., where the sensingelement can comprises an optical fiber. Alternatively, the sensingelement can comprise a thermal imaging element, or an ultrasound imagingelement, for example.

In a further aspect of the invention, the form about which the threedimensional shape is wound is formed from metal, ceramic or other heatresistant material and has formed within it the path desired for themicro-cable corresponding to the shape. For example, the form can be ofa spherical configuration, with the surface containing channels intowhich the cable is laid prior to heat treating. The channels can bearranged so that the resultant shape is kink resistant and relativelyeasy to withdraw without kinking. The form can also contain passagesthrough which the cable can pass to advantageously form the shape.

After the cable is wound around the form, the form and cable can be heattreated to cause the cable material to adopt the shape of the form as alow energy shape. The cable can then be removed from the form and putinto a catheter-introducer prior to use in intravascular therapy.

In another presently preferred embodiment, the invention comprises adevice for use in interventional therapy and vascular surgery, adaptedto be inserted into a portion of a vasculature, comprising a shapememory coil having an outer coil portion and an inner core portion, theshape memory coil having a collapsed primary coil configuration and anexpanded secondary configuration with a three dimensional shape; and aradiopaque strand extending through the core of the shape memory coil toprovide a radiopaque marker of the deployed configuration of the device.In one presently preferred embodiment, the shape memory coil comprises amulti-stranded coil having a plurality of flexible strands of aresilient material, and in an alternate preferred embodiment, the shapememory coil comprises a single stranded coil, such as of a nickeltitanium alloy, or a shape memory polymer, for example. The radiopaquestrand enhances the radiopacity of a multi-stranded coil, as well as asingle stranded coil of pure nickel titanium alloy, which willadvantageously not fray upon stretching, and is stretch resistant. Withsuch an inner radiopaque strand, the coil can also be made of othermaterials, such as a shape memory polymer such as polyurethane, forexample.

In a presently preferred embodiment, the radiopaque strand comprises acore strand having a plurality of intermittently spaced apart enlargedradiopaque portions that can comprise a radiopaque material selectedfrom the group consisting of platinum and gold, for example. The corestrand can comprise a material selected from the group consisting ofplatinum, gold, a shape memory polymer having a glass transitiontemperature (T_(g)) below 25° C., a hydrogel, an amorphous gel, and afiber. In one presently preferred aspect, the enlarged radiopaqueportions can comprise a plurality of beads of radiopaque material spacedapart and mounted on a core strand of material, and the beads maycomprise a radiopaque material selected from the group consisting ofplatinum, gold and tungsten. In another presently preferred aspect, oneor more of the plurality of beads can optionally be bonded to a segmentof the shape memory coil, such as an end bead bonded to an end segmentof the shape memory coil, for example.

In another presently preferred aspect, the enlarged radiopaque portionsmay comprise a plurality of coils intermittently wound about and spacedapart on the core strand, and the core strand can comprise a radiopaquematerial selected from the group consisting of platinum and gold. Thespaced apart coils can comprise a radiopaque material selected from thegroup consisting of platinum and gold.

In another presently preferred embodiment, a polyhedral occlusive deviceis provided, adapted to be inserted into a portion of a vasculature foroccluding a portion of the vasculature, for use in interventionaltherapy and vascular surgery. The occlusive device can be formed withmultiple coils centrally connected together at their inner ends to acentral coil body and radiating outward from the central coil body. Wheninserted within a vessel at a treatment site, such as within ananeurysm, the radiating coil arms of the occlusive device extend to fillthe vessel in three dimensions, allowing the occlusive device toaccommodate the shape of the vessel.

In another presently preferred embodiment, the device for use ininterventional therapy and vascular surgery includes a micro-cable orcoil formed of one or more flexible strands of a resilient material,having a collapsed primary coil configuration and an expanded secondaryconfiguration with a three dimensional shape; and one or moretherapeutic fibers woven into the coil to enhance treatment of the siteafter placement of the device. The coil can also be formed to includeone or more radiopaque strands to provide a radiopaque marker of thedeployed configuration of the device. The one or more therapeutic fiberscan be woven about adjacent or non-adjacent loops of the coil, or can bewoven through multiple strands of adjacent loops of the coil. The one ormore therapeutic fibers are made of a material that will provide a timedrelease of a therapeutic agent intended to become active after placementof the device, such as human growth hormone, collagen, a modifiedpolymer with growth factor, genetic material for gene therapy, antigens,or the like. A plurality of therapeutic fibers can be provided so thatthe different fibers in the coil can provide different therapeuticagents to provide a range of therapies.

These and other aspects and advantages of the invention will becomeapparent from the following detailed description and the accompanyingdrawings, which illustrate by way of example the features of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective of a radiopaque microstrand cable constructedaccording to the invention.

FIG. 2 is a cross-section at 2—2 of FIG. 1.

FIG. 3 is a helical vasoocclusive coil formed of the cable of theinvention.

FIG. 4 is a spherical vasoocclusive structure formed using the cable ofthe invention.

FIG. 5 is a stacked coil vasoocclusive device formed using the cable ofthe invention.

FIG. 6 is a cross section of a vascular member with an aneurysmillustrating the approach of a vasoocclusive coil towards the aneurysm.

FIG. 7 is an illustration of a vasoocclusive coil which has beenintroduced into an aneurysm preparatory to being deployed within theaneurysm.

FIG. 8 is an illustration of a spherical vasoocclusive coil formed withcable of the invention deployed within an aneurysm.

FIG. 9 is an alternate preferred embodiment of the invention including aplurality of radiopaque strands within the cable.

FIG. 10 is an alternate preferred embodiment incorporating a therapeuticmember within the radiopaque cable of the invention.

FIG. 11 is an alternate preferred embodiment of the present inventionwherein strands of the cable are arranged within an exterior bindingconsisting of multiple straps about the cable.

FIG. 12 is a perspective view of the embodiment of FIG. 11.

FIG. 13 is an alternative embodiment to the embodiment of FIG. 12wherein the external binding of the cable represents a sheath woundabout the cable.

FIGS. 14a and 14 b are perspectives of alternative embodiments of theembodiment of FIG. 13.

FIG. 15 is a cross-section of an alternative embodiment in which aplurality of multi-strand cables are included within an external sheathsurrounding the cable.

FIG. 16 is a perspective view of the embodiment of FIG. 15.

FIG. 17 is a plan view of a beaded radiopaque strand according toanother preferred embodiment of the invention.

FIG. 18 is a sectional view of the beaded radiopaque strand of FIG. 17inserted in a shape memory coil.

FIG. 19 is a plan view of an alternate preferred embodiment of aradiopaque strand with intermittent spaced apart coils.

FIG. 20 is a plan view of an alternate preferred embodiment of theradiopaque strand having spaced apart enlarged radiopaque portions.

FIG. 21 is a schematic diagram of a preferred three dimensionalradiating coil configuration of a primary wind polyhedral occlusiondevice according to the principles of the invention.

FIG. 22 is a schematic diagram of an alternate preferred embodiment of aprimary wind polyhedral occlusive device according to the principles ofthe invention.

FIG. 23 is a perspective view of a mandrel for forming the polyhedralocclusive device of FIG. 22.

FIG. 24 is a schematic diagram of an alternate preferred embodiment of asecondary wind polyhedral occlusive device according to the principlesof the invention.

FIG. 25 is a perspective view of another preferred alternate embodimentof a helical vasoocclusive coil according to the principles of theinvention, with a therapeutic fiber woven around adjacent loops of thecoil.

FIG. 26 is a perspective view of another preferred alternate embodimentof a helical vasoocclusive coil according to the principles of theinvention, with a plurality of therapeutic fibers woven around adjacentloops of the coil.

FIG. 27 is a perspective view of another preferred alternate embodimentof a helical multi-stranded vasoocclusive coil according to theprinciples of the invention, with a therapeutic fiber woven throughstrands of adjacent loops of a multi-stranded coil.

FIG. 28 is a perspective view of another preferred alternate embodimentof a helical multi-stranded vasoocclusive coil according to theprinciples of the invention, with a plurality of therapeutic fiberswoven through strands of adjacent loops of a multi-stranded coil.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

While nickel-titanium alloys are useful in forming super-elastic orshape memory interventional devices, micro-coils formed of very smalldiameter wires of nickel-titanium alloy material for treatment of areasof the small diameter vasculature such as an artery or vein in thebrain, for treatment of aneurysms and the like, for example, can haverelatively low yield strengths and are somewhat subject to kinking, evenif made of super-elastic alloy. This can create problems if the coil isto be withdrawn after being emplaced by the doctor, as for instance, ifthe device is too small to effectively fill the cavity to be treated.Furthermore, even solid wires of a size suitable for use ininterventional devices are not very radiopaque.

As is illustrated in the drawings, which are provided for the purposesof illustration and not by way of limitation, the invention is embodiedin a multi-stranded micro-cable formed of a plurality of flexiblestrands of a resilient material with the cable including at least oneradiopaque strand. In a presently preferred embodiment of the inventionillustrated in FIG. 1, the multi-stranded micro-cable 10 isapproximately from 0.0015 to 0.009 inches in diameter, and comprises aplurality of flexible strands 12 of nickel-titanium alloy, with at leastone centrally, axially disposed radiopaque wire 14 which isapproximately from 0.0005 to 0.003 inches in diameter. While the abovestated diameters represent those presently known to be compatible withthe invention, larger or smaller diameters may be useful for particularapplications. The central radiopaque wire 14 can be formed of platinumor gold, for example, or other similar suitable radiopaque metals, inorder to provide a radiopaque marker of the deployed configuration of adevice made of the cable during vascular surgery.

There are numerous benefits to the novel construction of the inventionfor use in interventional devices and the like. By using the stranded ormicro-cable construction of the invention, a device made from themicro-cable becomes virtually kink resistant compared to the singlestrand wires now commonly used in micro-coils. The multi-strand cableconstruction of the invention allows the micro-wires of the cable toslip across each other and reinforce each other rather than break ortake a set. Also, by incorporating a stranded radiopaque material suchas platinum, tungsten or gold into the cable construction, the device isradiopaque in sizes much smaller than with other constructions. Themicro-cable construction of the invention can be used to produce soft,kink resistant, radiopaque stents, guidewires, guidewire distal tips,and micro-coils.

FIG. 2 is a cross-section of the micro-cable of FIG. 1 at 2—2illustrating one presently preferred arrangement of the strands withinthe cable. In this embodiment, the exterior strands 12 are formed of aresilient material chosen to provide the characteristics desired for aspecific application in interventional therapies. In a presentlypreferred embodiment, this material is a nickel titanium super-elasticalloy which is heat treated such that the alloy is highly flexible at atemperature appropriate for introduction into the body via a catheter.By choosing such a material for micro-coils and the like, the devicesformed from the micro-cable can be relatively easily placed into theappropriate body cavity and after placement, the device will take on ashape designed to optimize the therapeutic purposes desired for thedevice. As illustrated in FIG. 2, such a cable can have a central core14 of a radiopaque material such as gold or platinum, thus dramaticallyenhancing the radiopacity of the cable. Even a solid super-elastic wireof the same diameter as the cable would have substantially lessradiopacity than the cable of the invention with the central gold orplatinum wire and the construction of the invention provides numerousother highly desirable characteristics. Among these characteristics isthe relative flexibility and resistance to kinking of the cable comparedto an equivalent single wire and substantially greater accommodation ofthe cable to bending, etc., with resultant lessening of trauma to thesurrounding tissue and ease of placement in a small body cavity.

One advantageous application of the invention is to vasoocclusivedevices formed of the micro-cable for insertion into aneurysms and othervascular defects for the purpose of occluding flow to the aneurysm. FIG.3 illustrates a helically wound coil 16 of micro-cable 10 which isformed to fit within a micro-catheter for insertion into an area uponwhich a therapeutic procedure is to be performed. While a helical coilis illustrated, it will be appreciated that numerous other secondaryshapes can be formed from the cable of the invention, as will bedescribed further below. More specifically, as illustrated in FIG. 4, athree dimensional, essentially spherical, device 18 can be formed of thecable 10, (or even of a coil of the cable, if appropriate) at atemperature sufficient to heat treat the material and thereby create amemory of the desired shape. The device is then inserted into a catheterfrom which it may be deployed into an aneurysm or the like. Theteachings of U.S. Pat. No. 5,645,558 describe the construction of such adevice out of flexible wire and are incorporated by referenced herein.FIG. 5 illustrates a collapsed coil configuration 20 for a vasoocclusivedevice which also can be formed from the cable of the invention and isused for the purposes of insertion into aneurysms and other defects thathave relatively large entry necks compared to their internal volume.

FIG. 6 is an illustration of a catheter 22 using a coil 16 as avasoocclusive device made of the present invention and used forinsertion into an aneurysm 24 projecting laterally from a blood vessel26. The coil 16 is contained within the outer housing 28 of amicro-catheter that is used to house the coil prior to deployment. Theend of the catheter housing 28 is introduced into the opening 30 of theaneurism 24 by use of a guide wire (note shown). Thereafter, thevasoocclusive coil 16, and a pusher 32 are introduced into the catheterto provide for insertion of the vasoocclusive device into the aneurysm.In a presently preferred embodiment, the coil 16 formed of the cable ofthe invention is retained to an optical fiber pusher 32 which isattached to the coil by a collar of shape memory plastic material 34 asdescribed in co-pending application Ser. No. 08/986,004 the disclosureof which are incorporated herein by reference. As shown in FIG. 7, thecoil is introduced into the aneurysm and is then pushed from themicro-catheter until it fills the cavity.

Those skilled in the art will recognize that it is sometimes the casethat the vasoocclusive device must be withdrawn after it is fully orpartly inserted into the aneurysm. In such a case, there is a dangerthat the coil will be stretched beyond its elastic range or kink, orotherwise deform and make withdrawal difficult. Those skilled in the artwill also recognize that it is sometimes advantageous to formvasoocclusive devices of secondary shapes which are based upon a basicconfiguration of a coil or the like. The present invention includes suchapplications within the scope of the invention. However, whenvasoocclusive devices made of even super-elastic material are used, itis sometimes the case that the devices will be stretched or kinked whenwithdrawal is attempted. The cable of the present inventionsubstantially reduces the probability that kinking or stretching beyondyield will occur in a given instance, while at the same time providingradiopacity not available with other constructions. Thus, the presentinvention represents an important forward step in the technology ofinterventional therapy.

In one presently preferred embodiment, the shape memory collar 34 isheated to a temperature which allows it to be shrunk onto coil 16. Thecollar is attached to optical fiber pusher 32 by an adhesive 36 whichretains high strength at temperatures beyond the shape memory materialtransition point. After insertion, and when the operator is satisfiedthat the device is properly deployed, light energy from a source ofcoherent light is introduced into the proximal end of the optical fiber(not shown) and propagated in the distal end 38 of the fiber to causethe shape memory material collar 34 to return to its previous shape andrelease coil 16. Those skilled in the art will recognize that theinvention can also be used with a variety of other placement cathetersystems, and it is not intended that the invention be limited to theplacement concepts illustrated by way of example.

Those skilled in the art will recognize that a number of shaped devicesmay be introduced into an area to be treated depending upon its geometryand the number of devices to be inserted. FIG. 8 illustrates anessentially spherical device 18 which has been deployed into such ananeurysm but it will commonly be found that a device such as that shownwould then be supplemented by a further coiled device inserted withinthe space inside the spherical device to completely occlude flow fromthe artery to the aneurysm.

While one presently preferred implementation of the micro-cable of theinvention has been illustrated, those skilled in the art will appreciatethat other variations of the invention may have advantages for certainpurposes. FIG. 9 is an example of one such construction 40 in whichradiopacity is more desirable than in other forms and for that reason anumber of radiopaque strands 42, in this illustration four in number,are formed into the cable along with three resilient material strands44. It will also be appreciated that a larger or smaller number ofstrands may be incorporated into a given cable and the cables may beformed of multiple cables in order to provide desired bending andstrength characteristics. It will also be appreciated by those skilledin the art that the invention is adaptable to the use of a variety ofmaterials which by themselves would not have been easily adaptable tomicro devices for interventional therapies. For instance, materials suchas copper are useful for intrauterine devices and the like, but copperwire, even when heavily alloyed, has certain limitations for use in suchdevices. By use of the present invention, composite cables incorporatingone or more strands of a desired material can be configured with otherstrands providing strength, flexibility, shape memory, super-elasticity,radiopacity or the like for previously unavailable characteristics inmicro devices.

The invention is also adaptable to numerous other purposes. FIG. 10illustrates a cross-section of a further preferred embodiment in whichradiopaque strands 42 and resilient strands 44 form a portion of thecable 46 and a therapeutic agent 48 is contained in one of the strands.Such a therapeutic agent can include human growth hormone, hydrogels, ora variety of other agents which will serve to provide desiredtherapeutic capabilities when placed within a specific area of the bodybeing treated by use of the micro-catheter. Depending upon theapplication of the therapeutic agent, its method of action and thedelay, if any, in the time after placement in which the therapeuticaction is desired, the agent strand may be placed in any of a variety ofpositions with the cable, from core wire outward. Also, it may bedesirable to coat one or more strands with a therapeutic material forcertain purposes. Such constructions are contemplated within the scopeof the invention.

It is also contemplated within the scope of the invention that one ormore of the strands of the micro-cable is longer than the others, andperhaps intermittently terminated, to thereby produce a micro-cable inwhich the therapeutic strands extend to a greater diameter than theother strands to thus increase the therapeutic effect of the therapeuticstand. Such a construction is particularly advantageous if increasedthrombogenicity is desired, while maintaining structural continuity andradiopacity for the micro-cable.

FIG. 11 illustrates a cross-section of an additional presently preferredembodiment of the invention in which the strands 12, 14 of themicro-cable 10 are bundled and banded at intervals by bands 50 toproduce a composite banded cable 52 in order to provide increasedflexibility without unraveling or dislocation of the strands in thecable. FIG. 12 is a perspective view of the banded cable 52 of thisembodiment. While the illustrated configuration shows the strands beinglaid parallel within the cable, it is also possible in this constructionto include both twisted cables as the primary cables 10 within the outerbands 50 to form the composite cable 52. This configuration can use oneor more longitudinal strands 14 which are radiopaque, thus providing acontinuous indication of radiopacity within the cable. As a furtheralternative embodiment, it is possible for the longitudinal cable 52 tobe formed of a single inner cable 10 with bands 50.

FIG. 13 illustrates a further embodiment of the invention in whichlongitudinal strands of cables 54 are contained within a wound cover 56for the purposes of providing a composite guide wire or the like 58having improved torqueability. Such a construction has particularadvantages for guidewire designs having improved radiopacity in verysmall diameters. It will be appreciated that in this configuration, aswell as the other longitudinally arranged multi-stranded cables, thenumber of strands and the degree to which they extend along the cablewithin the sheath is a variable which can be used to provide increasedstiffness, pushability and torqueability in some sections with greaterflexibility in others. Additionally, composite cables according to theinvention can incorporate additional elements normally not available insolid guide wires, such as optical, thermal or ultrasound imagingelements, therapeutic agent delivery catheters, and can take advantageof materials which are not readily adaptable to prior art catheter orguide wire designs incorporating a primary wire structured element.FIGS. 14a and 14 b illustrate a further variable available because ofthe invention; the exterior wrapped cover 56 can be wound at greater orlesser intervals 60 along the outside to provide variations in thetorqueability and stiffness of the composite cable. Also, the thicknessand width of the wrapping cover 56, as well as its material compositionalong the composite guide wire 58, can offer further capabilities forcustomizing the design for various applications. These advantages can becombined with the benefits of shape memory or super-elastic alloys tocreate guidewires and other devices with heretofore unavailablecapabilities.

FIG. 15 illustrates a cross-section of a micro-cable according to theinvention which has at least one overall exterior sheath to contain themicro-cable. The micro-cable may be made of one or more multiple strandelements which may further include twisted or longitudinal strandswithin their construction. The sheath may also be used to control thetorqueability characteristics of the cable and as discussed inco-pending application, Ser. No. 08/986,004, the sheath may bemulti-layered with different materials in order to provide a graduatedbending and stiffness characteristic over the length of the cable.

Referring to FIGS. 17 to 20, in another presently preferred embodiment,a nickel titanium alloy coil, such as the multi-stranded micro-cabledescribed above, can be made radiopaque by the insertion of a radiopaquestrand having spaced apart enlarged radiopaque portions into the core ofa primary and/or secondary wind. The radiopaque material preferably hasa desired degree of stiffness so as not to compromise the desired degreeof softness of the coil. The material may comprise a beaded core ofplatinum, gold, shape memory polymer having a glass transitiontemperature (T_(g)) below 25° C., polymer, hydrogel, and the like, or aflexible strand, rod, amorphous gel, fiber, and the like. The radiopaquestrand can be used to enhance the radiopacity of the multi-strandedcoil, as indicated above, as well as a pure nickel titanium alloy coil,which will advantageously not fray upon stretching, and is stretchresistant. With such an inner radiopaque strand, the coil can also bemade of other materials, such as a polyurethane shape memory polymer,for example.

In a presently preferred embodiment illustrated in FIGS. 17 and 18, theradiopaque strand 70 may comprise a plurality of beads 72 of radiopaquematerial, such as platinum, gold or tungsten, spaced apart and mounted,such as by soldering, welding, or adhesive bonding such as bycyanoacrylate adhesive, on a core strand 74 of material that can beplatinum, gold or tungsten, or a shape memory polymer having a glasstransition temperature (T_(g)) below 25° C. The beaded radiopaque strandcan form the central core of a multi-stranded micro-cable, and as isshown in FIG. 18, the beaded radiopaque strand 70 may form a core of apure nickel titanium alloy coil 76 wound around the beaded radiopaquestrand, and having a proximal stem 77 bonded to the coil by soldering,welding, adhesive or the like, that can also be formed as a radiopaquemarker, of such materials as platinum, gold or tungsten, for example. Ina preferred aspect, one or more beads, such as an end bead 78, mayoptionally be bonded to a segment 80 of the coil, such as bycyanoacrylate adhesive 81, for example.

In another presently preferred embodiment illustrated in FIG. 19, theradiopaque strand can comprise a radiopaque wire 82, such as platinum orgold, for example, intermittently wound with a plurality of spaced apartcoils 84 of radiopaque material, such as platinum or gold, for example,to form an inner radiopaque core for a multi-stranded micro-cable, or inan alternate preferred embodiment, the intermittently wound radiopaquestrand may form a core of a pure nickel titanium alloy coil wound aroundthe intermittently wound radiopaque strand.

Referring to FIG. 20, in another presently preferred embodiment, theradiopaque strand can comprise a radiopaque wire 86, such as platinum orgold, for example, with intermittently spaced apart enlarged radiopaqueportions 88, to form an inner radiopaque core for a multi-strandedmicro-cable, or for a pure nickel titanium alloy coil wound around theradiopaque strand.

It will be appreciated that a three dimensional occlusive device adaptedto be inserted into a portion of a vasculature for occluding the portionof the vasculature for use in interventional therapy and vascularsurgery, can be formed as described above, from at least onemulti-stranded micro-cable having a plurality of flexible strands of aresilient material, with at least one radiopaque strand to provide aradiopaque marker for the device during vascular surgery. The occlusivedevice is configured to have a primary coil shape, as illustrated inFIG. 5, and an expanded secondary three dimensional coil configurationor shape, that can be generally helical, conical, or spherical shapes,such as the spherical shapes illustrated in FIGS. 4 and 8. A mandrelsuitable for making such three dimensionally shaped occlusive devicescan be formed of a refractory material, such as alumina or zirconia, forexample. The mandrel typically has the general three dimensional shapethat the occlusive device will be given, and can have a generallyhelical, conical, or spherical shape, or can have a unique shapedesigned to provide such a form to the occlusive device to fit aparticular vascular structure to be treated. The mandrel forms a supportfor the winding and heat treatment of the micro-cable, plurality ofmicrocables, or composite micro-cable occlusive device as describedabove, and ideally will not contaminate the occlusive device during heattreatment of the device. The surface of the mandrel preferably has aplurality of circumferential grooves for aligning the occlusive deviceas it is wound on the mandrel. The surface of the mandrel may also haveone or more apertures for receiving one or more ends of the micro-cable,plurality of microcables, or composite micro-cable, to assist windinginto the desired form.

The wound occlusive device is then heat treated at a suitabletemperature and a sufficient period of time to impart the form to theshape memory material included in the device. While heat treatment at atemperature of about 1100° F. for approximately 4 hours or more istypically sufficient to impart the form to the occlusive device when theshape memory material is a nickel titanium super-elastic alloy, but whenthe occlusive device includes fibers or a therapeutic agent that can beaffected by heat, the temperature utilized can be substantially lowered,and the duration of heat treatment adjusted accordingly, as will beappreciated by those skilled in the art. Alternatively, if thetherapeutic agent is not amenable to elevated temperatures, it may beadded after formation of the three dimensional shape. After the heattreatment, the occlusive device is removed from the mandrel, and coldworked into the desired collapsed primary configuration for placementinto a catheter or cannula for use. It will be appreciated that thosetechniques can also be used for a variety of cables produced accordingto the invention, including those which use shape memory materials otherthan nickel-titanium alloys. When the occlusive device reaches itsdestination in the vasculature during vascular therapy, it assumes thesecondary relaxed and expanded three dimensional shape imparted from theheat treatment on the mandrel.

In another presently preferred embodiment, a three dimensional,polyhedral occlusive device is provided, adapted to be inserted into aportion of a vasculature for occluding a portion of the vasculature, foruse in interventional therapy and vascular surgery. The occlusive devicecan be formed as described above, from at least one multi-strandedmicro-cable having a plurality of flexible strands of a resilientmaterial, with at least one radiopaque strand to provide a radiopaquemarker for the device during vascular surgery, with multiple coils,preferably four or more coils, centrally connected together at theirinner ends, and in a presently preferred aspect, connected at theirinner ends to a central coil body and radiating outward from the centralcoil body. When inserted with a vessel at a treatment site, such aswithin an aneurysm, the radiating coil arms of the occlusive deviceextend to fill the vessel in three dimensions, allowing the occlusivedevice to accommodate the shape of the vessel. In a preferred aspect,the radiating coils of the occlusive device can thus form a tetrahedral,pentahedral, hexahedral, or other polyhedral shape, symmetrical orunsymmetrical, and are preferably formed from conically shaped coil armsthat have an expanding diameter as they radiate outward from the centralcoil body, with the radiating coil arms having soft larger diameterouter ends. The central coil body may be spherical or rounded, or may becorrespondingly cubical, tetrahedral, pentahedral, or otherwiseappropriately polyhedral. A typical aneurysm may have a diameter ofapproximately 10 mm., and the coil arms will also typically have anouter diameter of approximately 10 mm.

As is illustrated in FIG. 21, one presently preferred three dimensionalradiating coil configuration 90 is a primary wind coil having ahexahedral configuration with six conically shaped coil arms 92radiating from a central coil junction 94 in the three x, y and z axesof a three dimensional pattern of coordinates. Such a three dimensionalradiating coil configuration can be formed by individually winding theradiating arms of the hexahedral configuration on conically shapedmandrel, and bonding the inner apical ends 96 of the coils together bywelding, solder, adhesive such as cyanoacrylate, or the like. A centralcoil body 98 such as the spherical coil described above is alsopreferably similarly bonded to the inner ends of the coil arms.

Referring to FIG. 22, in another presently preferred embodiment, a threedimensional radiating hexahedral coil configuration 100 for theocclusive device is also a primary wind coil with six conically shapedcoils or coil arms 102 radiating from a central coil ball or sphere 104in the three x, y and z axes forming a three dimensional pattern ofcoordinates. The central ball may also alternatively have the shape of acube, for example. The outer diameter of the coil arms typically can beapproximately 10 mm., and the diameter of the central coil ball orsphere typically can be 3 mm. in diameter. The hexahedral coil can beformed by winding the central spherical coil about a mandrel asdescribed above and then joining the six radiating conical coil arms attheir inner apical ends 106 to the central spherical coil 108, asdescribed above, such as by welding, solder, adhesive such ascyanoacrylate, or the like. Alternatively, the hexahedral coilconfiguration can be formed as a continuous primary wind of the coil bywinding the central spherical coil, and forming the radiating arms by adouble winding of the radiating conical coil arms, first up from thecenter and then back down, with each of the radiating conical coil armsbeing wound in turn about the central spherical at the appropriatelocation.

Referring to FIG. 23, such a hexahedral configuration with six conicallyshaped coils radiating from a common central coil ball or sphere can beformed by winding the coils about a mandrel 110 formed of a refractorymaterial, such as alumina or zirconia, for example, and having invertedconical coil arms 112 radiating from a central body 114, such as aspherical, rounded, cubical, tetrahedral, pentahedral, or otherwisepolyhedral central body, for example. The mandrel forms a support forthe winding and heat treatment of the three dimensional radiatinghexahedral coil occlusive device as described above, and ideally willnot contaminate the occlusive device during heat treatment of thedevice. The surface of the central body of the mandrel preferably has aplurality of circumferential grooves 116 for aligning the occlusivedevice as it is wound on the mandrel. The surface of the mandrel mayalso have one or more apertures 118 for receiving one or more ends ofthe micro-cable, plurality of microcables, or composite micro-cableforming the hexahedral occlusive device, to assist winding into thedesired form.

In another configuration illustrated in FIG. 24, a another presentlypreferred alternate three dimensional radiating coil configuration 120is a secondary wind coil of a primary wind coil, such as a helical wind,for example, the secondary wind coil having a hexahedral configurationwith six conically shaped coil arms 122 radiating from the commoncentral coil 124, which is illustrated as having a cubical shape, in thethree x, y and z axes of a three dimensional pattern of coordinates. Theouter diameter of the coil arms typically can be approximately 10 mm.,and the diameter of the central coil ball or sphere typically can be 3mm. in diameter. The hexahedral secondary wind configuration can beformed by winding the primary helical wind coil about an appropriatemandrel, and then joining the six radiating conical coil arms at theirinner apical ends 126 to the common central coil 128, as describedabove, such as by welding, solder, adhesive such as cyanoacrylate, orthe like. Alternatively, the hexahedral coil configuration can be formedas a continuous primary wind of the coil by winding the central coilbody, and forming the radiating arms by a double winding of theradiating conical coil arms, first up from the center and then backdown, with each of the radiating conical coil arms being wound in turnabout the central spherical at the appropriate location.

As is described above, the tetrahedral, pentahedral, hexahedral or otherpolyhedral wound occlusive device radiating from the common central coilis then preferably heat treated upon the mandrel at a suitabletemperature and for a sufficient period of time to impart the relaxedform to the shape memory material forming the device. The occlusivedevice can then be cold worked into a shape suitable for deliverythrough a catheter to a desired treatment site, and when the occlusivedevice reaches its destination in the vasculature during vasculartherapy, it assumes the relaxed and expanded three dimensional shapeimparted from the heat treatment on the mandrel.

In another presently preferred embodiment illustrated in FIGS. 25 and26, a helical microcoil 130 that can be formed of one or more flexiblestrands of nickel-titanium alloy, has one or more therapeutic fibers 136advantageously woven about adjacent loops of the coil, used to enhancetreatment of the site after placement of the device. The helicalmicrocoil can also be formed to include one or more axially disposedradiopaque wires, as described above. Alternatively, the one or moretherapeutic fibers can be woven about non-adjacent loops of the coil aswell. The therapeutic fibers are preferably made of a material that willprovide a timed release of a therapeutic agent, such as human growthhormone, collagen, a modified polymer with growth factor, geneticmaterial for gene therapy, antigens or the like, that are intended tobecome active after placement. When multiple fibers are provided, as isshown in FIG. 26, different fibers can be provided in the same coil withdifferent therapeutic agents to provide different therapies. The fibersare preferably woven into the coil by hand after the heat setting of thecoil shape.

In another presently preferred embodiment illustrated in FIGS. 27 and28, a helical microcoil 140 formed of a plurality of flexible strands142 of nickel-titanium alloy, with at least one centrally, axiallydisposed radiopaque wire 144 as described above, has one or moretherapeutic fibers 136 as described above, advantageously woven throughthe multiple strands of adjacent loops of the coil, to enhance treatmentof the site after placement of the device. Alternatively, the one ormore therapeutic fibers can be woven through the strands of non-adjacentloops of the coil as well. When multiple fibers are provided, as isshown in FIG. 28, the different fibers can be provided in the same coilwith different therapeutic agents to provide different therapies. Theone or more fibers are preferably woven through the strands of themultiply-stranded microcoil by hand during winding of themultiply-stranded microcoil.

It will be apparent from the foregoing that while particular forms ofthe invention have been illustrated and described, various modificationscan be made without departing from the spirit and scope of theinvention. Accordingly, it is not intended that the invention belimited, except as by the appended claims.

What is claimed is:
 1. A device for use in interventional therapy andvascular surgery, adapted to be inserted into a portion of avasculature, comprising: a shape memory coil having an outer coilportion and an inner core portion, and said shape memory coil having acollapsed primary coil configuration and an expanded secondaryconfiguration with a three dimensional shape; and a radiopaque strandextending through the core of the shape memory coil to provide aradiopaque marker of the deployed configuration of the device, saidradiopaque strand having a plurality of intermittently spaced apartenlarged portions disposed within said shape memory coil.
 2. The deviceof claim 1, wherein said shape memory coil comprises a multi-strandedcoil having a plurality of flexible strands of a resilient material. 3.The device of claim 1, wherein said shape memory coil comprises a singlestranded coil.
 4. The device of claim 3, wherein said single strandedcoil comprises a nickel titanium alloy.
 5. The device of claim 3, hereinsaid single stranded coil comprises a shape memory polymer.
 6. Thedevice of claim 1, wherein said enlarged portions comprise a radiopaquematerial selected from the group consisting of platinum and gold.
 7. Thedevice of claim 1, wherein said enlarged portions comprise a pluralityof beads of radiopaque material spaced apart and mounted on a corestrand of material.
 8. The device of claim 7, wherein said beadscomprise a radiopaque material selected from the group consisting ofplatinum, gold and tungsten.
 9. The device of claim 7, wherein at leastone of said plurality of beads is bonded to a segment of the shapememory coil.
 10. The device of claim 7, wherein an end bead is bonded toa segment of the shape memory coil.
 11. The device of claim 1, whereinsaid enlarged portions comprise a plurality of coils intermittentlywound about and spaced apart on said core strand.
 12. The device ofclaim 11, wherein said core strand comprises a radiopaque materialselected from the group consisting of platinum and gold.
 13. The deviceof claim 11, wherein said spaced apart coils comprise a radiopaquematerial selected from the group consisting of platinum and gold. 14.The device of claim 1, wherein said core strand comprises a materialselected from the group consisting of platinum, gold, a shape memorypolymer having a glass transition temperature (T_(g)) below 25° C., ahydrogel, an amorphous gel, and a fiber.